Telephone system



May-12, 194,2.

R. SCHWARTZ TELEPHONE SYSTEM Fi1ed March 2o, 1959 l May l2, 1942.

R'. sczHwARTz TELEPHONE SYSTEM Filed March 2o, 1959 s sheets-sheet 2 kmmx t6 n `N ENA.,

ROMAN scHwARrz ATTRNEY. v

May 12, 1942.

R. SCHWARTZ *2282893 TELEPHQNE SYSTEM Filed March 20, 1939 y3 Sheets-Sheet 5 PSX ENS. I SN ROMAN SCHWARTZ- Patented May 12, 1942 TELEPHONE SYSTEM Roman Schwartz, Berlin-Wilmersdorf, Germany,

assignor to Fides Gesellschaft fur die Verwaltung und Verwertung von gewerblichen Schutzrechten m. b. H., Berlin, Germany Application March 20, 1939, Serial No.

rmany March 26, 1938 `n1 Ge 19 Claims.

In remote signalling in particular telephone installations it is known-that a party on a party line does not connect himself to the party line by making a call, but ried out in such a manner that switch means at his branch set are controlled by switching devices, which are arranged in an exchange accessible to the party line. Thus, for example, under the control of a call impulse transmitted from a branch set in the exchange, various marking signals associated with the individual branch sets are connected to the party line. After each signal has been connected a testing operation follows to see Whether the branch set marked by this connection is the calling one.

The invention avoids the successive connections'of the various marking signals to the party line and the testing following on each connection as to the calling condition of the marked branch set, in that by means of an impulse train sent out from and characterizing the calling branch set (pre-setting impulse train) switching devices in the exchange are controlled, which bring about the transmission of only the marking signal associated with the calling branch set and under the control of this signal and of the calling condition of the calling branch set the latter is connected to the party line by the selecting device that this connection'is carchange associated with the party line.

and the connecting means of the calling branch set.

If the impulse train, whichmarks the calling branch set, is sent out automatically on the lifting of the receiver, the necessary period for building up an outgoing connection and hence, the seizing period of the party line are reduced con!- siderably.

If the impulse train marking the branch set of the calling subscriber is transmitted by special operation of the dial switch, then on the average the time'for connecting the branch set to the party line is not essentially shorter than in the arrangement mentioned above, but the danger of false connections is considerably reduced. These false connections occur when the calling subscriber operates his dial switch before receiving the exchange signal indicating that he may begin with the impulse transmission for setting up the connection. With the arrangement according to the invention, since the completion of the impulse train takes place directly the connection of the calling branch set tak-es place, the subscriber can begin immediately with the impulse selection for setting up the connection. The period which the calling subscriber had to wait is cut out.` o

Ll'igure 3 is a collection of the marking features associated with the individual branch sets. In it the wiring of the junctions I-S at the individual branch sets can be seen.

I. The branch setsrASt' makes a call and is connected The subscriber of the branch set ASt takes up his instrument. Thel hook switch contact hu6I is closed and the hook switch contact hu6II opens after a time. The ringing circuit is completed: earth, contact llbB, windings I and II of relay S116, hook switch contacts huSII, huGI, impulse contact nsi, junction l, conductor la, contact lZba, 13121, Mg, |510, |60, winding I of relay A11., The relays S106 and An operate. The relay S176 short circuits its winding I at contact Hsp and at contact I 8sp6 prepares a holding circuit over its winding III. Y

The relay An locks up over: wiper 26 of the indicating selector KWI, normal position of the same, contact Zlan, winding II of relay An, At contact 22cm the setting of the characterizing selector KWI is prepared. The relay A is applied to the conductor Ala over the contact 23an. At contact 24cm the relay J is connected, which opens contact 25j andcloses 2 67. The negative pole of a battery of |20V is applied over resistance 21 to the conductor Ib. The lamps, which are in the branch sets of the conductor ib light up and the B-relays connected in series with them operate. In the exchange the lamp Gla cannot light up and the relay ABa is not energized, since earth is disconnected at contact 28cm. Y.

The energizing circuit for the B-relay of the branch sets AStS and AStG shown in Figure l extends as follows: -|2QV, resistance 27, contact 26j, lead l b, branch set ASt5: junction 8, lamp GIS, windings I and II of relay B5, earth and branch set AStB; junction 8, lamp GIB, windings I and II of relay B6, earth. The contacts I|b6 (in AStB), 29b5, (in AStE) are opened and the contacts 36126 (in AStS), 3lb5, (in AStS)l are closed. By the operation of the B-relaysV all branch sets with the exception of the calling branch set AStS are guarded, since by the opening of the contact 29b5 and ofthe corresponding nals from the calling branch set by means of the pre-setting impulse train sent out. At theV The selecting devices are later controlled by connection of particular marking sigbranch set ASt6 the selecting `device to which the resistances 65 and 66 in the condenser KOB appertain is connected over the contact 61116 and the conductor resistances 62, 63 are connected as well as the condenser Ko over the contact 64125.

The relay S126 at the calling branch set AStiremains energized in a circuit extending over the relay VA in the exchange: earth, contact 36b6, winding III of relay S176, contacts I8sp6, 3256, huBI, ns1', junction 1, lead la, contacts Izba, 23cm, relay A, contact 33uI, resistance 34, The relay A operates and connects the relay VI `contacts 35112 and |1533, 36a, relay VI, resistance 31, The relay V2 connected over contact 38vI cannot operate since it is short circuited over the contacts 36a and 35111 or I15. At contact 390| the circuit over the rotary magnet Dkwl of the indicating selector KWI is prepared.

It is assumed that the presetting impulse train, which marks the calling branch set is not sent out automatically on the lifting of the receiver but that the calling subscriber selects his own characterizing digit 6. By using specially constructed dial switches with special iinger holes for the pre-setting impulse train the subscribers of all branch sets must operate the dial switch from this special linger hole Vafter calling. The dial switches are however so constructed that only the impulses corresponding to the characterizing digit of the set are sent out as after the transmission of these the impulse contact mi is Vshort circuited by the closing of the contact usa,

The impulses of the pre-setting impulse train are transmitted to the exchange by the impulse accepting relay A over the rotary magnet Dlcwi of the indicating selector KWI -I-, contacts 221m, 43a, 39m, 44pI, 45p, rotary magnet DkwI, During this impulse train the relay V2 is also energized since on the opening of contact 36a the short-circuit is removed from the windings I and II. At contact 46112 it short circuits its winding II and holds therefore during the momentary closing of contact 36a. Over the contact 41122 the winding II of the relay An, remains energized after the wiper 26 has left its normal position. Also the relay VI holds during the impulse transmission and the momentary closing of contact 48a.

At the end of the pre-setting impulse train the relay A remains energized. The contact 36a is permanently closed and therelay V2 restores. At contact 41112 the relay An is disconnected. Over the contact 281m -l- (earth) is applied to the winding of the relay Ba so'that since -I2IJV is still connected over contact 267' to the conductor Ib the lamp Gla lights up and relay Ba operates. At the same time the relay P is energized: contact 490|, 56cm, relay P, The contact -5Iba is parallel to contact 490| so that relay P remains energized after the release of relay VI. Over-the series contacts |310, 52g/ and Ia. At the branch set ASt the setting impulse train by means of a selector KWI and associated with the calling set is then applied to the party line.

Figure 3 shows the marking signals associated with the branch ASH to 8 of the party line. It is clear that in order to connect each branch set a current of particular polarity or and of particular duration (short or long) is necessary and that further the holding windings of a connecting relay are connected either to the conductor Ia or to the conductor Ib.

For connecting the branch set AStS the transmission of a long impulse over the party line is necessary. The holding of the connecting relay R6 takes place over the conductor Ib.

The selection of the connecting signal takes place by means of the characterizing selector KWI set by the pre-setting impulse train and the wipers of this selector` rest on the contact 6 in their contact bank. In order to connect a calling branch set only the switching operations carried out over the wipers 20, 54 and 55 are of importance.

The selecting impulse initiating the connection of the calling branch set AStB extends over the following circuit: contact 6, wiper 54 of the characterizing selector KWI, contacts 56m, 60j, 6Iba, conductor Ia, at all branch sets over the condensers Ko to earth, and actually at the branch set ASt5 shown over junction 1, resistance 62, 63, junction 3, I, contact 64b5, condenser Ko5, earth and the calling branch set ASt6 over junction 1, resistance 65, 66, junction 3, I, contact 61126, condenser KOB, earth. The condensers over two series resistances corresponding to the resistances 65, 66 (AStS) are also connected at the branch sets 1 and 8 as is clear from the table. At thebranch sets I to 4, .at which the junctions I and 2 are connected the condensers are only connected over the resistance corresponding to the resistance 65 (AStB) at the junction 1 and hence in the conductor Ia.

For the complete charging of the condenser at the branch sets 5 to 8 as already mentioned a longer impulse is necessary. The relay J is disconnected by the opening of contact 52g on the release of relay VI, over relay Y connected over the contacts 68p and 69UI which locks up over Winding II and the contact 1611/. The contact 607' is opened after a time in which only the condensers at the branch sets I to 4 can be cornpletely discharged over a resistance connected to the conductor Ia. In order to increase the length of the selector impulse and hence the charging period for the condensers the slow relay E energized over the wiper 20 of the indicating selector KWI and the contact 511i retards the release of the relay J. Over the normal contact 12e the condenser Koa is charged. On the operation of the relay E and the closing of the contact 14e there follows the discharge of the condenser Koa over the relay J after the opening of contact 52y. During the discharging of the condenser Koa the relay A remains energized in its discharged circuit. This perlod is extended so that at the Vbranch'sets 5 to 8 the condensers are completely charged.

After the release of the relay J a discharging circuit is closed over the conductor la of the party line in order that the condensers at the branch sets I to 4 may be discharged. Also the condensers at the branch sets 5 to 8 are partially discharged. Since the discharging circuit at these branch sets extends over two series resistances as also does the charging circuit then 'for example as the branch sets ASt5 and AStB over the two series resistances 62, 63 or 65, 66 these condensers still have sufcient charge after the opening of the discharging circuit to enable the operation of the connecting relay (relay R5 at ASt5 and relay R6 at AStB) in a local discharging circuit.

After the discharge of the condenser Koa of the relay J among other things the contacts 257, j are closed and the contacts 267', 607, 511i are opened. The relay Ba in the exchange and also the B-relays of the branch sets remain energized however since over the contact 16e the current source 120V is still connected to the conductor Ib. During the release period of the relay E earth is connected over the contacts 11e, 15?', 6|bal to the conductor a and thus the discharging circuit for all the condensers is set up at the branch sets.

The relay E restores, disconnects earth from the conductor la at contact 11e and at contact 16e: 120V from the conductor Iab. The latter is switched through at contact 18e. Relay Ba in the exchange and the B-relays at all the branch sets restore. 'I'he conductor la is switched through at |2ba. The condensers at the branch sets are disconnected from the conductor la and connected in local discharging circuits over the normal contacts of the B-relay.

At the branch ASt5 this local discharging circuit of the condenser K05 extends over the contact 19125 and the winding I of relay R5 and at the branch set AStG over the contact 80176 and the winding I of relay R6. The relays R5 and R6 operate and kamong other things connect their holding windings II by closing the contacts 8|r6 and 8215. The same takes place at the branch sets ASt1 and AStS. At the branch set ASt5 and also at the branch set ASH the holding windingv l1 of the connecting relay is connected withV the conductor la over the junction 1 while at the branch sets AStS and at the branch set ASt8 the holding windings II of the R-relays are connected over the junction 8 on the conductor Ib.

A further distinction in the connecting signal of a branch set is that the holding winding of the relay R may be connected with the conductor la or with the conductor Ib. Corresponding to the branch sets to be connected the pole of the central battery which is not earth is connected to the conductor la or to the conductor Ib in the exchange. In order to connect up the branch set AStG the unearthed pole of the central battery is connected over resistance 34 contact 33ul, relay A, contacts 83y, 84w to the conductor Ibi. Holding current can accordingly not flow over the relay R5 of the branch set ASt5 also energized but only over the relay R6 of the branch set ASt6. It has already been explained that at the branch sets ASt1 and AStB the condensers can operate the connecting relays in their discharging circuit. The holding windings at the branch set ASH are also connected to the conductor la as is clear from Figure 3. These relays can accordingly not hold' and restore. The holding winding of the connecting relay of the branch set AStB is connected over the'latter to the branch set AStB on the conductor Ib. The release of this relay is thus carried out so that the holding winding of the relay at the branch set ASt is connected in opposite direction to that at the branch set AStS, i. e., the junctions 4, 6, and 5, 8 are connected with one another. The holding circuit over the windingII of the connecting relay of the branch set ASt8 elTects the de-polarizing of the connecting relay which accordingly restores.

` Therefore only the connecting Arelay R6 at the branch set ASt6 remains energized.

On the call from the branch set ASt5 at the end of the pre-setting impulse train the wipers of the indicating selector KW| rest on contact 5. After the energizing of the relay Ba the relay UI is energized: contact 811m-, wiper-55, selector contact 5, relay Ul, The relay A tted with the slow armature attraction and release is `connected: contact 88g, 85ml, relay U2, The relays U| and U2 effect the disconnection of kfrom the conductor lb and the connection of the unearthed -lpole of a central battery to the conductor la, since the holding winding II of the connecting relay R5 is applied to the conductor la after the selecting of the branch set ASt5. At the contact 9|u| earth is connected over resistance 93 to conductor Ib and at contact 92u| is connected over resistance 94 to the conductor la. Thereupon by the opening of contact 33u11 is disconnected from the conductor |b| and by the opening'of contact 8911A earth is disconnected from the conductor |a. The slowly operating relay U2 which also connects the relay Ul in a local holding circuit over its contact 95u2, connects earth over the lower resistance 95 and the contact 91u2 to the conductor Ib and over the lower resistance 98 and the contact u2 to the conductor la. The holding circuit of the winding II of the relay R5 accordingly extends as follows: resistance 98, contact 99u2, choke DM, contacts |0011, llw, |2b'a, conductor la, branch set AStS, junction 1, 6, winding II of relay R5, junction 5, 4, contacts 82r5, |02s5, earth. The connection of an unearthed -1- pole of a second current source to the conductor Ia instead of the switching over of the unearthed pole of the central battery from the conductor Ib to the conductor la is necessary from the point of View of operating technique for connections between two subscribers of the same party line (for reasons not of interest within the scope of the present invention).

In the circuit over the holding winding II of the relay R6 the relay A in the exchange operates. The relay Vl is energized. Since also the relay Y is energized the conductors |06 and |01 are switched through. 'Ihe choke DTZ is therefore now in bridge across the conductors |06 and |01 leading to the selector VW. The call relay of the pre-selector not shown operates. The preselector isset on a free outgoing junction line.

By the energizing of the connecting relay R6 there follows also the connection of the instrument which is indicated by the microphone Mz' to the party line. Moreover the circuit over the holding winding II of the relay R6 is as follows:

|2ba, conductor la, junction 1, contact mi, huBI, |0815, winding I of relay S6, microphone Mz', contacts |09b6, ||0r6, junction 8, conductor lb, contacts 257', 18e, 84w, 83g, relay, A, contact 33m, resistance 34, The relay S6 operates. yIt closes the contacts |||s6 Aand ||4s6 parallel to the contacts |r6 and |0816, Adisconnects earth from the holding winding II of the connecting relay R6 at contact ||2s6 so that this relay restores whereby the dissymmetry of the talking line is removed and` at contact ||3s6 short circuits the winding I of the relay B6 for reasons not of interest here. Further the contact 32s6 is also opened. y

The connection of the branch set AStS .to the party line is complete. Y

The selecting devices at the branch sets consisting of condenser resistance arrangements are controlled at the completion of the pre-setting impulse train sent out from the calling branch set by means of selecting current of particular direction and duration bringing about the connection of the calling branch set.

vAfter the opening of contact 6921i the relay Y remains connected over its winding II and the contacts 10g, 68p. Further the relay Vl has undertaken the necessary switching operations for setting up a required connectionduring the transmission to the party line.

The relay G operates over its winding I: contacts ||4p, H511. ||6y, ||1h, winding I of relay G, Moreover it closes contact ||8g and opens contact |19g.

The transmission of the pre-setting impulse train results not only in the connection of the connecting signal associated with the calling branch set AStB but also a momentary connection of the associated meter in the exchange. As described the wipers of the indicating selector KWI rest on Contact 6. Over the wiper |03 the meter Z6 is connected parallel to the locking winding ci the cut-off relay Tr of the; pre-selector VW and can be operated in some way'or other either on the reply of the selected subscriber or during the connection or at the termination of the conversation.

When at the termination of a connection of the calling subscriber of the branch set AStG with a subscriber of a distant line or at the termination of a connection with a subscriber oi the same party line both subscribers give the terminating signal by hanging up their receivers, the feeding bridge relay A in the exchange restores. At contact 48a the release retarding relay VI is shortcircuited. It brings about the disconnection of all relays of the party line still energized.

The release of the indicating selector KWI set by means of the pre-setting impulse train on the initiating of a connection is performed by the connection of the rotary magnet Dkwl, in the following circuit: rotary magnet Dkwl, contacts p, 44pl, 400|, relay G, winding II, vertical ofi normal contact |80lclcw|, interrupter RU, The indicating selector KWI steps on to its normal position and is there stopped to open the circuit indicated above at contact |80kkwl. The relay G guards the party line in the usual manner during the release.

The rest position of the device in the exchange is again set up,

At the branch set ASt6 on the hanging up of the hand instrument the relay S6 is disconnected since the contact huBI is opened. Itrestores and at the branch set sets up the normal condition again.

I1. The branch sets ASt are called So long as the party line of a subscriber has taken a branch set into use a seizing of the latis opened. On the setting of the test wiper of the final selector LW on the contact 6 associated with the required branch, e. g., ASt the test relay P w cannot operate.

If lon the setting of the final selector on the junction ASt6 the party line is free the test circuit is completed: test relay Plw, wiper |85, contact 6, resistance |81, contact |8|g, |82a n, |83a, |8417, relay C, resistance |88, The `test relay Plw switches through in the iinal selector in the usual manner. The seizing relay C locks up over contact |890 independently of the contacts |8|g to |8411 and at contact |900 connects the Winding I of the relay P| to the wiper 56 of the indicating selector KWI.

The seizing circuit of the party line does not extend over the cut-off relay -associated with the party line. This is connected in a local circuit by means of the seizing relay C: contact 200C, normal contact 20| of the preselector VW, wiper |10, cut-off relay Tr, In known manner it cuts off the calling bridge from the conductors |06 and |01. At contact |69c the parallel path, containing the meter Z6 of a required br-anch set, to the winding shown of the cut-off relay. Tr is opened so that on the energizing of the relay M resulting on the reply of the required branch set and closing of the contact |68m there is no energizing of the meter Z6.

The indicating selector KWI which on the call of a branch set is set by a pre-setting impulse characterizing the latter and by connecting 'of the connecting signal of the party line brings about the connection of a calling branch set serves also to connect the connecting signal for the branch set selected at the iinal selector on the seizing of the party line over a final selector. Thev contacts of the nal selector are connected with the .contacts of the contact bank indicated by the wiper 56 of the indicating selector KWI. The indicating selector KWI is started up on the closing of a circuit for the driving magnet Dlcwl at contact |920: rotary magnet Dkwl, contacts 45p, 44pl, 400|, |920, vertical off` norl mal contact |9|lckw|, interrupter RU, The

indicating selector. executes a single step, the vertical oif normal contact |9|klcw| is opened and the vertical off knormal contact |80kkw| is closed.` The circuit for the rotary magnet Dkwl now extends over this contact and the contact |199. When the wiper 56 of the indicating selector reaches contact 6 the relay PI is energized: winding I of relay Pl, contact |900, wiper 56, contact 6 on the indicating selector KWI, and on the final selector LW, wiper |85, test relay Plw, The relay P| operates and by opening contact 44p| stops the indicating selector KWI. The relays H and A are connected: relay H, contacts |93pl, |9411, and resistance 34, contact 33ul, relay A, contacts 2|2y, |pl, |96ba, (earth). Over the contacts 36a and 35w or |1511: the relay Vl is connected and over contact 49M energizes the relay P. The relay J is energized: |45w, |4611, rel-ay J, resistance |98,. In the manner already described 20V is applied to the conductor Ib over the contact 265i. The B-relays at all the branch sets and the relay Ba in the exchange operate. At contact |96ba the circuit over the relay A is opened, the relay and hence -also the relay Vl restore.

' By the setting of the'indicating selector KWI corresponding to the'branch set indicated at the final selector the connection of the impulse of long duration bringing about thec-onnection of the branch set AStB to the conductor la is prepared. After the release of the relay VI and closing of contact 591A there follows the charging of the condensers at the branch sets in the manner described in section I by means of the current source connected over wiper 54 of the indicating selector KWI and the selector contact 6.

The relay Y is energized: contacts- 68p, 691;! winding I of relay Y, At contact 10 it connects its Winding II in a holding circuit, opens the contact 2|2y and closes the contacts '83g and muy.

'I'he relay W is energized: 6912i, |48h, relay W, The contact 35w in the circuit of the relay Vl is opened. Further, the short circuit over windings I and II of the differential relay X is removed by the opening of contacts Ilw and 8410. The relay X operates in the circuit extending'over its winding I and serving to maintain the energization of relay R6 at the branch sets and opens the contact |1511: in the circuit of the relay VI and the contact |601: in the circuit of the relay M. Although the holding circuit of the relay R6 extends over the relay A which operates, the relay VI cannot be energized since both contacts 3510 and |'I5x are opened.

Over the contacts |5010 the circuit of the call relay Rr is closed. The relay R1' operates for example every 5 seconds when is connected over the time switch 5". At contact I 5311' the winding I of the relay X is short vcircuited and at contact |55rr the alternating current source is connected to the conductor la. The call current operates the bell of the selected branch. set AStB: call current source, contacts |55rr, |54u2, I2ba, conductor la, junction 1, 9, contact 220r6, bell, earth.

When the called branch set AStG replies the winding I of relay S6 is connected between the conductors la and Ib: conductor la, contact nsz', huEI, I 0816, winding I of relay S6, instrument, contact IIJSbS, llllr, junction 8, conductor Ib. The relay S6 operates, closes the contacts H456 and `I|Is6 parallel to the contacts l0816 and |lr6. It opens the holding circuit over the winding II of the relay R6 at contact I I2s6. The dissymmetry of the line set up after the selection of the branch set AStB is thereby removed. In the exchange the dilerential relay X restores. It closes the contact I 60x. At contact |153: the circuit of the relay Vl is closed, the relay operates and among other things prepares the circuit of the relay G at contact IISUI. The relay M operates: contacts Idlvl, |66w, |6012, relay M, The contact llm is opened and the contact Ilim is closed. The meter Z6 does not operate however since the contact 169C is opened.

At Contact I Hm the holding circuit over the relay I-I is opened. The relay H restores and at contact lllh closes the circuit for the relay G: contacts H410, H5211, Il6y, Il'lh, windings I of relay G, At contact I'lllg the short circuit for windings II and the circuitV of the rotary magnet Dlcwl is removed and at contact 202g the short circuit forthe seizing relayC is prepared.

The release of relay H also brings about the disconnection of the relay W by opening of the contact |48h.. At the contacts Ilw and 84w the windings of the differential relay X are short circuited. At contact IUw the @all relay Rr kis disconnected.

contacts 68p,

When at the termination of the connection the subscriber of the branch set AStB hangs up his instrument the relays A and VI restore. By means of the contacts |8411, |83a, I82an, 22q the seizing relayC is short circuited and restores. Among other things the Contact |900 is opened and thus the test relay PI disconnected. This relay restores and at contact 44p! closes the circuit of the rotary magnet Dcwl. The indicating selector steps on to its normal position.

By the opening of the contact |c the test relay Plw of the nal selector restores and brings about its release.

What is claimed is:

l. In a telephone or like system, an exchange, a partly line terminating at said exchange, a plurality of stations on said line each having a device normally disconnected from the line, means at each of said stations operated at times while the device at that station is disconnected from the line to transmit over said line to the exchange impulses characteristic of that particular station, means at the exchange controlled by said impulses for transmitting over the line a selecting impulse characteristic of said station, and means at each station for connectingV up the device at that station responsive only to the receipt of a selecting impulse characteristic of that station;

2. In a telephone or like system, an exchange, a partly line terminating at said exchange, a plurality of stations on said line each having conversational equipment, means at each station normally disabling the conversational equipment thereat, means at .each of said stations operated when the subscriber thereat desires to extend a call for transmitting over said line to the exchange a Vtrain of impulses characteristic of that particular station, means at the exchange controlled by said impulse train for transmitting over the line a selecting impulse characteristic of the calling station, and means at each station for rendering the disabling means thereat ineffective responsive only to the receipt of a selecting impulse characteristic of that station.Y y

3.v In a system as claimed in claim 2, a plurality of devices at the exchange each individual to one of the stations on said line, said means at the exchange controlled by the impulses transmitted from the calling station to connect up the device individual to said calling station.

4. In a telephone or like system, an exchange, a, party line terminating at said exchange, a plurality of stations on said line each having a devicenormally disconnected from the line, means at each station for connecting the device at that station to the line, means at the exchange for controlling said last means to connect the device at any one of line, and means at any calling one of said stations for transmitting impulses characteristic of that station over the line to the exchange to control said means at the exchange to cause the device at said calling station to be connected to the line.

5. In a system. as claimed in claim 4, means operated on an incoming call to any of said stations to control said means at? the exchange to cause the device at that station to be connected to said line.

6. In a telephone or like system, an exchange, a. partly line terminating plurality of stations on said line each having the stations alone to the at said exchange, a

6 means for transmitting distinctive impulses thereover to the exchange, and means at the exchange automatically controlled by the impulses received over said line from one of said'stations to transmit over said line a station selecting impulse varying in duration depending upon said received impulses.

7. In a telephone or like system, an exchange, a partyV line terminating at said exchange, a plurality of stations on said line each having means for transmitting distinctive impulses thereover to the exchange, and means at the Aexclange controlled by the impulses received over said line from one of said stations for transmitting over said line a station selectingl impulse depending in duration and polarity upon said received impulses.

8. In a system as claimed in claim 7, a device at each station normally disconnected from the line, and means at each station for connecting the device thereat to the line responsive to the receipt over the line from the exchange of a station selecting impulse of a particular duration and polarity.

9. In a system as claimed in claim 7, conversational equipment `at each station, means at each station normally disabling the conversational equipment thereat, and other means at each station for renderingv said disabling means ineffective responsive to the receipt over the line from the exchange of a station selecting impulse of a particular duration and polarity.

10. In a telephone system, an exchange, a party line terminating at the exchange, a plurality of stations on said line each having means operated at times from the exchange to unbalance said line, means in the exchange controlled by the unbalancing of said line by the means at one of said stations lfor transmitting ringing current over the line to signal said one station, and means for balancing said line responsive to the subscriber at said one station answering said signalling, thereby to control said last means to terminate the transmission of said ringing current.

11. In a telephone or like system, a substation and a line therefor, a relay at said substation,

means at the substation controlled over said line to connect said relay to said line, means responsive to said connecting of said relay to said line for causing ringing current to be impressed upon the line to signal said substation, and means for disconnecting said relay from said line responsive to the subscriber at said substation answering said signalling, thereby to cause said last means to stop impressing said ringing current upon the line.

l2. In a telephone or like system, a substation and a line therefor, said substation having a ringer and a relay each normally disconnected from said line, means controlled over said line for connecting said relay to said line, means controlled by said connecting of the relay to said line for causing ringing current to be impressed upon the line, means for maintaining said relay operated over said line until the subscriber at said substation answers the ringing, said relay effective while operated to maintain said ringer connected to saidv line.A

13. In a telephone or like system, a substation and a line therefor, said substation having a ringer and a relay each normally disconnected from said line, means controlled over said line ior connecting said relay to one side of said line, means controlled by said'connecting 'of said relay to said one side of the line for causing ringing current to be impressed on the other side of said line, means for maintaining said relay operated over said one side of the line until the subscriber at said substation answers'the ringing, said relay effective while operated to maintain said ringer connected to said other side of said line.

14. In a telephone or like system, an exchange, a party line terminating at saidA exchange, a plurality ofstations Yon said line, means for initiating a call from any of said stations, a register at said exchange, means for controlling said register over said line to register the identity of the calling station whenever a call is initiated from one of said stations, 4means then controlled by said register totransmit over said line from said exchange an impulse depending in duration upon the identityof said calling station, said impulse being of different duration'for the different stations, normally disabled equipment at each of said stations, and means at each station controlled. by said impulse transmitted from the exchange to render said equipment at that station effective if said impulse is of a particular duration. i

15. In a telephone or like system, an exchange, a party line terminating at said exchange, a plurality of stations on said line, means for initiating a call from any of said stations, a register at said exchange, means for controlling said register over said line to register the identity of the calling station Whenever a call is initiated from one of said stations, means then controlled by said register to transmit over said line from said exchange an impulse depending in duration and polarity upon theidentity of said calling station, normally disabled equipment at each ofY said stations, and means at each station controlled by said impulse transmitted from the exchange to render said equipment at that station effective if said impulse is of a particular duration and polarity.

16. In a telephone or like system, an exchange, a party line terminating at said exchange, a plurality of stations 4on said line, means for initiating a call from any of said stations, a register at said exchange, means for controlling said register over said party line to register the identity of theY calling station whenever a call is initiated from one of said stations, and means then controlled by said register to transmit over said line from said exchange a station selecting impulse depending in duration upon the identity of said calling station, said impulse being of a different duration for the different stations.

1'7. In a telephone or like system, an exchange, a party line terminating at said-exchange, a plurality of stations on said line, means for initiating a call from any of said stations, a register at said exchangeJ means for controlling said register over said party line to register the identity of the calling station whenever a call is initiated from one of said stations, and means then controlled by said register to transmit over said line from said exchange a station selecting impulse depending in duration and polarity upon y the identityof said calling station.

18. In a telephone or like system, an exchange, a register at the exchange,va party line terminating at said exchange, a plurality of stations on said line, subscriber controlled means at each of said stations for operating said register varably over said party line, and means controlled subscriber controlled pulse varying in duration depending upon the way in which said register was operated by said means 19. `In a telephone or like system, an exchange, a register at the exchange, a party line terminating at said exchange, a plurality of stations on 10 iably' over said vmzfity line, and means controlled by said register after said operation thereof by4 said subscriber controlled means to transmit over said line from said exchange a station selecting impulse depending in duration 'andpolarty upon the way in which said register was operated b said subscriber controlled means.

' ROMAN SCHWARTZ. 'I

said line, subscriber controlled meansrat 'each of said stations for operating said register varg 

